Door latch apparatus



A ril 28, 1970 s. G. M BURNIE DOOR LATCH APPARATUS 2 Sheets-Sheet 1Filed Jan. 3, 1967 E u w ZJ. M j W E m m RM r m E 5 v I u m m f e m w w/W W WW 0 v w $5 A m M mrm W\ 77/ W n mroauevs 4 w 3 g 7 7... 1 i 7 a M am 4 m w ,z Al f-"tr I. A!

April 28, 1970 s. G. MCBURNIE 3,508,777

DOOR LATCH APPARATUS Filed Jan. U, 1967 2 Sheets-Sheet 2 ATTORMEY UnitedStates Patent O.

US. Cl. 292-254 12 Claims ABSTRACT OF THE DISCLOSURE An apparatus forlatching a door and having a housing which is adjustable lengthwise. Across shaped shaft extends through the housing and handle knobs aresecured to the shaft, the knobs being journalled on housing parts. Aspring pressed latch plate on the door jamb normally holds the doorclosed and a plunger is mounted in the door between the shaft and thelatch plate. Rotation of one of the handle knobs in either directionwill operate the plunger to depress the latch plate and unlatch thedoor.

BACKGROUND OF THE INVENTION This invention relates to apparatus forlatching a door and more particularly to mechanism for manuallyreleasing an automatically operating latch bolt or the like.

Most latch sets presently in use are costly items to manufacture due inpart to the complexity of the devices and the fact that many of themetal parts require precision machining and other finishing. Also thetask of assembling the numerous parts which make up the conventionallatch set is time consuming and this is reflected in the selling priceof the manufacturer. The eventual purchaser of such a set is usuallyfaced with the added expense of hiring a skilled workman to install theset in the door and with the current high cost of labour this factormust be given consideration by the average home owner.

SUMMARY OF THE INVENTION The present invention is made almost entirelyof plastic and the design of the apparatus is such that the severalparts can be made by a relatively simple and inexpensive injectionmolding process. Such a process produces finished parts which can bedistributed and sold without assembly to effect a correspondingreduction in the selling price of the apparatus. The apparatus is onewhich can readily be installed by an unskilled householder or workmanusing simple tools and if certain errors are made in preparing the doorto receive the device, the present apparatus will compensate for atleast some of the miscalculations and still operate effectivelythereafter.

A further feature of the invention resides in the provision of a shaftwhich requires only a small amount of plastic material to form but whichpossesses the strength and rigidity of the conventional metal shaft usedin a latch set. The shape of the plastic shaft is such that it can bethreaded to receive the handle knobs, and said knobs can readily bekeyed to the non-corrosive shaft.

Another advantage derived from the invention is the means wherebyrotating parts of the apparatus are journalled in the door. No specialbearings are required for this purpose and the ones provided by thedesign of the apparatus ensure proper alignment and function of therotating parts. Since the bearing surfaces as well as other parts of theapparatus are formed of suitable plastic materials, no lubrication isrequired and the action of the device is exceptionally quiet and smoothoperating.

In order to achieve the above features and advantages as well as otherswhich will later appear, the invention contemplates a housing which ismounted in the door 'ice near the free edge thereof. A shaft extendstransversely through the housing and the door and novel means isprovided to journal the shaft in the housing. The shaft has a number ofradial ribs which are engaged by a yoke on the end of alatch operatingplunger. The shaft and the yoke have mating parts which interlock saidshaft and yoke and also provide a cam action whereby rotation of theshaft in either direction will reciprocate the plunger.

BRIEF DESCRIPTION OF THE DRAWING FIGURE 1 is a sectional plan of theapparatus,

FIGURE 2 is a view taken on the line 22 of FIG- URE 1,

FIGURE 3 is a view taken on the line 3-3 of FIG- URE 1,

FIGURE 4 is a view taken on the line 44 of FIG- UR'E 1,

FIGURE 5 is a view taken on the line 5-5 of FIG- URE 1,

FIGURE 6 is a view tatken on the line 66 of FIG- URE 5,

FIGURE 7 is a view taken on the line 77 of FIG- URE 1, and

FIGURE 8 is a view taken on the line 8-8 of FIG- URE 4.

DESCRIPTION OF THE PREFFERED EMBODIMENT Referring to the drawings, thenumeral 10 indicates generally a door having an inside face 11, anoutside face 12 and a side edge 14. The door 10 closes against a jamb 16of the door frame, the jambbeing fitted with an abutment strip 17.

Unless otherwise stated, all parts of the present apparatus are made ofa suitable plastic material. The apparatus includes a keeper or latchplate 20 which is mounted in a supporting frame 21, the frame beinginlaid into the edge of the jamb 16 with the right side edge of saidframe aligned with the adjoining face of the strip 17, see FIG- URE 1.The frame 21 is secured to the jamb by means of metal screws 22. Plate20 has integrally formed pintles 23 (FIGURE 2) at the corners of itsupper and lower edges and these pintles are lodged in grooves 24 formedin the adjacent edges of the supporting frame opening 25. The grooves 24extend inwardly from the rear face of the frame 21 and terminate shortof the exposed face of said frame. The edge 26 of the plate 20 abuts theadjacent edge 27 of the frame 21 to limit inward movement of said latchplate. Thus the latch plate 20 is supported in upright position in theframe 21 by the pintles 23 and a spring 28 fitted to said plate normallyurges the latch plate outwardly of the opening 25, the plate then beingdisposed at a slight angle to the outer edge of the door. Since thespring 28 is formed of a resilient plastic material, it conveniently canbe molded as an integral part of the latch plate 20.

FIGURE 1 illustrates the manner in which the door 10 is prepared toreceive the present apparatus. A large hole 30 is bored transverselythrough the door from one face to the other at the same level as thelatch plate 20. A smaller hole 31 is drilled in the door edge 14, theaxis of the hole 31 being normal to the edge 14 and intersecting theaxis of the hole 30 at right angles. The door edge 14 is then recessedas at 32 to receive a strike 34.

The strike 34 is secured within the recess 32 by metal screws 35, seeFIGURE 5. A hole 36 is provided in the strike 34 at mid-height, whichhole registers with the hole 31 in the door. The hole 36 communicateswith a tapering recess 38 which is formed in the outer face of thestrike 34 to receive the inclined latch plate 20. The recess 38 providesa stop 39 against which the slightly rounded edge 40 of the plate 20 isadapted to bear to latch the door in closed position.

It will be seen in FIGURE 1 that the right edge of the strike 34 isflush with the face 12 of the door. When the door 10 is closed, thisright edge of the strike abuts the strip 17 of the jamb whereupon therecess 38 is in proper position to receive the latch plate 20. The edge40 of the latch plate bears hard against the stop 39 and holds the doorclosed so that it cannot rattle. During installation, it is onlynecessary to align the frame 21 and the strike 34 vertically, theseparts being accurately located horizontally when they are correctlypositioned relative to the abutment strip 17 as above described. Thusinstallation is a relatively simple matter and the need to locate thestrike by the usual method of measuring, marking and adjusting isobviated.

Fitted to the door 10 is a housing 44 consisting of an outer sleeve 45and an inner sleeve 46. Sleeve 45 has an end flange 48 extending normalthereto and in which a central opening 49 is formed. The outer face ofthe flange 48 is provided with a shallow depression 50 which is circularand concentric to the opening 49, the bottom of said depression beingnormal to sleeve 45. Threads 51 are cut on the inner surface of thesleeve 45.

The inner sleeve 46 is a relatively short member which is externallythreaded as at 53 to engage the threads 51 of the outer sleeve. Sleeve46 has an end flange 54 extending normal thereto and which is providedwith a central opening 55 extending through a concentric depression 56,the bottom of said depression being normal to sleeve 46.

It will be noted the hole 30 is purposely made slightly larger than theoutside diameter of the sleeve 45 and that no particular care need betaken to ensure that the axis of said hole is truly perpendicular to thefaces 11 and 12 of the door. When the sleeves 45 and 46 are threadedtogether, their respective flanges 48 and 54 are moved into clampingengagement with the door faces. This has the effect of aligning thehousing so that the housing axis is normal to the door faces regardlessof the relative position of the axis of the hole 30 or the fact that theperiphery of the hole may be uneven. The housing sleeves are tightenedby hand, vis. no special tool is used for this purpose. The plasticflanges 48 and 54 have a natural tendency to cling or adhere to the woodof the door and a much greater hand pressure must be exerted in order toseparate the sleeves. To further ensure that the sleeve 45 cannot rotatein the door, said sleeve is provided with a radially projecting lug 58,see FIGURES 1 and 7, which bites into the wood of the door when the twosleeves are finally tightened. Thus the self-aligning and self-lockinghousing 44 does not require the usual screws or other fasteners tosecure it to the door. Also the same housing and its associated partsmay be used on doors of varying thicknesses with the same results, forexample, it could be adjusted to fit doors of up to about 3 inches inthickness.

Extending through the openings 49 and 55 is a shaft 60 having radialribs 61. The ribs 61 extend from end to end of the shaft and preferably,four such ribs are provided at 90 intervals about the shaftcircumference so that said shaft is seen as a cross when viewed in endelevation. A plastic shaft 60 of the described shape has ample rigidityand strength for the purpose it serves in the apparatus. The outer edgesof the ribs 61 are radiused about the longitudinal axis of the shaft andformed on these edges at each end of said shaft is an interrupted thread63.

Two of the ribs 61 are vertically disposed above and below the shaft 60.These two vertical ribs are offset intermediate their length to providenotches 64. As viewed in FIGURE 5, the notches 64 open out from theright side of the shaft 60 and the horizontal rib on the same side has anotch 65 which is aligned with the notches 64. As shown best in FIGURESand 6, the outer sleeve 45 of the housing has a hole 68 and the sleeve46 has a cut out 69 registering with the holes 31 and 36, and projectingthroungh these aligned holes and cut out is a cylindrical plunger 70.The plunger 70 has a rounded outer end 71 which projects into the recess38 in the strike 34. Interconnecting means is provided between the innerend of the plunger and the shaft. In this example, a yoke 72 isintegrally formed on the inner end of the plunger. The yoke 72 hasinwardly projecting arms 73 which extend over the vertical ribs 61, andbetween these two arms the inner edge of the yoke is recessed as shownat 74 in FIGURE 5. The recess 74 has substantially the same shape as thecross sectional profile of the adjoining portions of the shaft 60 atnotches 64 and 65 into which yoke 72 fits. The yoke is a loose fit onthe shaft 60 but is prevented from moving endwise of the shaft by thenotches 64 and 65 on the ribs, thus the yoke is self-aligning. A spring76 encloses the plunger 70 between the strike 34 and yoke 72. Rotationof the shaft 60 in either direction will cause the plunger 70 to moveendwise and compress spring 76.

Mounted on the ends of the shaft 60 are handle means in the form ofhandle knobs 80 and 81. As shown in FIGURE 1, the left or inside knob 80has a peripheral wall 83 which tapers inwardly to a base 84. The base 84has a suitably threaded opening 85 which enables the knob to be threadedon to interrupted threads 63 on the end of the shaft 60. Knob 80 isreceived in the shallow depression 50 on the flange 48. The right oroutside knob 81, which has a similar wall 87 and base 88 provided with athreaded opening 89, is similarly lodged in the depression 56 of theinner sleeve flange 54 when said knob is threaded on shaft 60. Shaft 60has a diameter considerably smaller than the openings 49 and 55 throughwhich it projects. Thus the depressions 50 and S6 serve as thrusthearings in which the handle knobs, and the shaft supported thereby, arerotatively mounted. Thus, the bases 84 and 88 in depressions 50 and 56act as means for rotatably supporting the shaft in housing 44. It willbe recalled that the flanges on the sleeves 45 and 46 and the bottoms ofdepressions 50 and 56 are parallel to the faces 11 and 12 of the door.The axis of the shaft 60 is therefore normal to the door faces and theseveral parts are properly related to one another even if the door isslightly warped or the opening 30 is inaccurately bored. Since theplastic knobs have sliding contact with the plastic housing, aparticularly quiet and smooth acting hearing is provided which does notrequire lubrication.

The outer handle knob 81 is non-rotatably secured to the shaft 60 bymeans of a key 90, see FIGURES l and 3, which key is square in crosssection. A notch 91, shown in FIGURE 3 only, is cut into the threads ofthe opening 89 in the knob 81. The cross sectional dimensions of the keyare such that said key will snugly fit between two adjacent ribs 61 onthe shaft with one edge of the key entering the notch 91. The key 90 maybe inserted in this manner by pressure applied by hand. When the key 90is so inserted, the handle knob 81 cannot be moved relative to the shaft60.

FIGURES l and 7 show the means of securing the inner handle knob 80 tothe opposite end of the shaft 60. A lock washer 93 is used for thispurpose, the washer having a cross-shaped opening 94 which conforms tothe cross sectional shape of the shaft 60. A number of circumferentiallyspaced and inwardly projecting tabs 95 are provided on the outer edge ofthe washer 93. The base 84 of the handle knob has a similar number ofslots 96 of corresponding shape and spacing. The lock washer 93 fitsover the end of the shaft and seats against the base 84 with the tabs 95lodged in the slots 96. The outer face of the washer 93 is provided witha pair of small handles 97 by which the locking device may be insertedinto the handle knob or removed therefrom. The knob '80 is thusnonrotatably secured to the shaft 60 and may be adjusted lengthwisethereof, with the Washer 93 enabling the knob to be locked in a numberof selected positions on the shaft.

In FIGURES 1, 4 and 8, the numeral 101 indicates a pin which isintegrally formed on the base 84 of the inner handle knob 80 to projectinwardly therefrom parallel to the axis of the shaft 60. An arcuate slot102 is formed in the depressed portion of the flange 48 and the pin 101extends into this slot. Normally the pin 101 is centrally located in theslot 102 as shown in FIGURE 4, and travel of the pin in a circular pathobviously is limited by the length of the arcuate slot. Thus the shaft60, and the knobs 80 and 81, keyed thereto, can be turned only a limitedamount in either direction. Because of the limited rotation of the shaft60, the plunger 70 cannot be projected far enough beyond the door edge14 so that, when the door is closed, the end 71 of said plunger willstrike the inner face of the door jamb 16.

The hollow handle knobs 80 and 81 are closed by means of covers or discs104 and 105. In FIGURE 1 the numerals 106 and 107 indicate rebates whichare provided on the outer edges of the walls 83 and 87 to receive thesediscs. The discs 104 and 105 are made so that their exposed faces areslightly convex as shown in dotted lines and while in this position saiddiscs are inserted into the snug fitting rebates 106 and 107. Whenfinger pressure is applied to the centres of the discs they snapinwardly whereupon their exposed faces are slightly concave. Thus thediscs are securely attached to handle knobs and can only be removed bymeans of a tool having a point which can be entered into holes, notshown, which are formed in the discs for this specific purpose.

The operation of the apparatus will be easily understood from theforegoing description and the drawings but briefly latching andunlatching of the door is accomplished as follows. When the door isclosed, the strike 34 momentarily depresses the latch plate 20, afterwhich the stop 39 is engaged by the edge 40 of the latch plate. The dooris now latched and can be opened only by turning either of the handleknobs 80 or 81 in either direction. Rotation of one of the knobs rotatesthe shaft 60 whereupon the plunger 70 is projected outwardly to dislodgethe latch plate 20 from the stop 39. When this is done, the door 10 canbe swung open and the knob released. Upon release of the knob used tounlatch the door, the spring 76 moves the plunger inwardly and thismovement of the plunger causes the shaft 60 to rock back to its originalposition.

It will be apparent that the present apparatus is extremely easy toinstall and that once the door is bored as described and the edges ofthe jamb and the door are suitably mortised, no additional tools arerequired.

The plastic parts do not corrode so that there is no likelihood of theapparatus sticking or becoming inoperative due to a build up of rust assometimes does happen with latch sets constructed of metal. In addition,the exposed portions of the device can be produced in a wide variety ofcolors which will last indefinitely. The elimination of metal bearingsurfaces results in a door latch apparatus which is quiet, very smoothworking and practically free from wear. This was proven by a testconducted to measure the wearing properties of the various parts of theapparatus. In this test, the apparatus was connected to a motor drivenapparatus which repeatedly unlatched the door, opened it, then closedand relatched the door. These movements were conducted at a frequency ofapproximately 100 times per minute over an extended period of time atthe end of which no appreciable signs of wear were detected in theapparatus.

Most existing door sets are made of metal and contain linkages requiringcertain forms of pin joints and sliding contacts which in the confinesof a lock are generally quite small. They are, then, subject toappreciable wear, and in time may become slack and possibly fail.

In the present invention, the transfer of manual pressure to release thelock is effected by compression contacts of several surfaces which aregenerous in area, so reducing unit pressures. Most of these contacts areof a rolling nature and only one is a sliding contact. These featuresaccount partly for the freedom from wear. The balance is accounted forin the choice of plastic material used, which by its nature is moreelastic and more wear resistant than many metals.

What is claimed is:

1. Door latch apparatus comprising a housing adapted to be placed in arelatively large hole extending through a door near an edge thereof, endflanges fixed on the housing adjacent opposite ends thereof andextending normal thereto, said flanges being adapted to engage oppositesurfaces of the door properly to position the housing in the door holeand relative to said surfaces, a shaft extending longitudinally throughthe housing centrally thereof, said shaft havinglongitudinally-extending ribs disposed at right angles to each other,means rotatably mounting the shaft in the housing, handle knobs, outsidesaid flanges and threaded to adjacent ends of the shaft by means ofwhich said shaft can be rotated, a plunger mounted in the housing forendwise movement on an axis normal to the longitudinal axis of saidshaft, said plunger being adapted to extend through a hole in the doornormal to said large hole and opening out through said door edge,interconnecting means between the plunger and said shaft and shaped tocause the plunger to move endwise upon rotation of the shaft in eitherof opposite directions, said means rotatably mounting the shaft in thehousing comprising bases on said handle knobs fitting in depressionformed in said end flanges and rotatably bearing against bottoms of saiddepressions properly to position and align the shaft relative to theflanges and said housing, said bottoms extending normal to the housing.

2. Door latch apparatus as claimed in claim 1, and including a strikeadapted to be secured to said edge of the door, said strike having anopening into which said plunger extends, and stop means on the strikeadjacent said opening.

3. Door latch apparatus as claimed inclaim 2, and including a latchplate-adapted to be swingably mounted on a door jamb in which said dooris fitted, said latch plate being opposite said strike and plunger,spring means normally urging the latch plate outwardly to engage saidstop means when the door is closed, said latch plate being disengagedfrom said stop means by movement of the plunger outwardly of the door.

4. Door latch apparatus as claimed in claim 3, in which theaforementioned parts are formed of plastic material.

5. Door latch apparatus as claimed in claim 1 in which each handle knobis hollow, means in each handle knob for locking each one to. the shaft,said means for lock ing one handle knob to the shaft comprising a lockwasher non-rotatably connected to the shaft, and circumferentiallyspaced tabs projecting from said washer, said one handle knob havingslots therein into which said tabs project.

6. Door latch apparatus as claimed in claim 5 in which said means forlocking the other handle knob to the shaft comprises a key fitting inregistering slots in the shaft and said other handle knob.

7. Door latch apparatus comprising a longitudinally contractable housingadapted to be placed in a relatively large hole extending through a doornear an edge thereof, end flanges fixed on the housing adjacent oppositeends thereof and extending normal thereto, means for contracting thehousing to draw the flanges against opposite surfaces of the doorproperly to position the housing in the door hole relative to saidsurfaces, said end flanges having depressions formed therein withbottoms extending normal to the housing and with openings in saidbottoms, a shaft extending longitudinally freely through the hous ingand the end flange openings, handle knobs outside said flanges andconnected to adjacent ends of the shaft by means of which said shaft canbe rotated, bases on said handle knobs fitting in said flangedepressions rotatably bearing against the depression bottoms properly toposition and align the shaft relative to the flanges and said housing, aplunger mounted in the housing for endwise movement on an axis normal tothe longitudinal axis of said shaft, said plunger being adapted toextend through a hole in the door normal to said large hole and openingout through said door edge, and interconnecting means between theplunger and said shaft and shaped to cause the plunger to move endwiseupon rotation of the shaft in either direction.

8. Door latch apparatus as claimed in claim 7 including means on saidhousing adjacent one of said end flanges for biting into said door whenthe housing is contracted to prevent rotation of the housing in saidfirst-mentioned hole of the door.

9. Door latch apparatus as claimed in claim 7 in which said handle knobsare threaded on the ends of said shaft, and including means for lockingone handle knob to the shaft and comprising a lock washer non-rotatablyconnected to the shaft, and circumferentially spaced tabs projectingfrom said washer, said one handle knob having slots therein into whichsaid tabs project.

10. Door latch apparatus as claimed in claim 7 in which said handleknobs are threaded on the ends of said shaft, and including means forlocking one handle knob to the shaft and comprising a key fitting inregistering slots in the shaft and said one handle knob.

11. Door latch apparatus ,for door having a first hole extendingtherethrough from face to face thereof and near one of its edges, and asecond hole therein extending from and normal to the first hole andopening out through said door edge, said apparatus comprising a housingadapted to be placed in the first hole and extending through the door,said housing being made up of telescoping outer and inner sleevesthreadedly connected together so that the housing can be longitudinallyextended and contracted, end flanges fixed on the housing sleevesadjacent opposite ends of the housing and extending normal to the axisof the housing, said flanges being adapted to engage the opposite facesof the door properly to position the housing in the first hole with saidaxis extending normal to the faces, a shaft extending longitudinallythrough the housing and through openings in the flanges, handle knobsoutside said flanges and connected to adjacent end portions of the shaftby means of which said shaft can be rotated, said handle knobs rotatablybearing against the flanges properly to position and align the shaftrelative to the flanges and said housing, a plunger adapted to extendthrough the second hole in the door and through a hole inthe housing andmounted for longitudinal movement along an axis normal to thelongitudinal axis of said shaft, and interconnecting means between theplunger and said shaft and shaped to cause the plunger to movelongitudinally upon rotation of the shaft in either direction.

12. Door latch apparatus as claimed in claim 11, in which said housingis formed of a plastic material to permit self-aligning and self-lockingengagement with the opposite faces of the door.

References Cited UNITED STATES PATENTS MARVIN A. CHAMPION, PrimaryExaminer E. J. MCCARTHY, Assistant Examiner US. Cl. X.R. 292-357, 350

